2-nitro-anthraquinone-7-sulpho-acid and process for making the same



Patented June 16, 193i WAUKEE, WISCONSIN,

s'r'rns IVAN G'UBELMANN, HENRY J. WEILAND,

ASSIGNORS, BY MESNE ASSIGNMENTS, T0 NEVTPORT CHEMI- AND OTTO STALLIJIANN, OF SOUTH M'ILr CAL CORPORATION, A CORPORATION OF DELAWARE" Z-NITRO-ANTHRAQUINONE-7-SULJEfI-IO-ACID AND PROCESS'FOR MAKING SAME No Drawing.

This invention relates to Q-nitrO-anthraquinone-Y-sulpho-acid and to a process for making the same.

It is an object of this invention to provide a simple and economical process for preparing 2-nitro-anthraquinone-7-sulpho-acid.

Other and further important objects of this invention will become apparent from the disclosures in the following description and appended claims.

WVe have now discovered that lsulpho-Q- benzoyl-5-nitro-benzoic acid described and claimed in our copending application, Serial No. 203,259, filed July 2, 1927, under certain conditions loses one mole of water and closes the ring to form 21iitro-anthraquinone-T- sulpho-acid. To the best of our knowledge this is the first beta-nitro-anthraquinonesulpho acid which has been described. It is likewise the first description of a process of successful ring-closing of a nitro-benzoylbenzoic acid. This latter part was quite unexpected inasmuch as attempts to ringclose many other nitro-ortho-benzoyl-ben- ZOlO acids were without success.

The method of removing one mole of water and closing the ring of 4=-sulpho-2-benzoyl- 5-nitro-benzoic acid is probably best accomplished by the use of strong sulphuric acid (oleum) as the dehydrating agent. However, we do not desire limiting the process to any particular procedure, as we have found that the elimination of water can be effected under various conditions of acid concentration and temperature and that other dehydrating'agents, such as phosphorous pentoxide, sodium acid sulphate, phosphoric acid and the like, react also to prepare the product, but are not economicallyso practicable as is our preferred method.

The reaction is most probably best expressed by the following chemical equation in which M represents a metallic radial like sodium, hydrogen, or the like Application filed July 2, 1927. Serial No. 203,261.

2 anitro anthraquinone 7 snlpho acid (mono-sodium salt) crystallizes from hot water in the form or" small white needles. It is fairly soluble in hot water and less so in hot dilute acid. It is sparingly soluble in cold water and practically insoluble in, cold dilute mineral acid, cold caustic soda or-in brine. It is likewise practically insoluble in glacial acetic acid or chloro-benzene; Re ducing reagents react on it to give Q-amino anthra'quinone Z sulphO-acid.

lVithout limiting our invention to any particular procedure,the following example, in which parts by weight are given, illustrates the application of our invention in the preferred form:

573 parts of crude l-sulpho-2-benzoyl-5- nitro-benzoic acid (mono sodium salt), equivalent to 373 parts of 100% material are dissolved in 1330 parts of 25% oleum, heated to 145 to 150 C. andkept at this temperature for about hour. The mass is now cooled down to 100 C. and. run in a thin streaminto'6000 parts of hot water. The diluted mass is cooled to room temperature, after which the precipitated product, 2-mtro-anthraquinone-7-sulpho-acid (.mono sodium salt), is filtered off, washed with cold water and then dried.

Since the principle of the process is the same whether the free acid or the sodium sals of ersulpho-2-benzoyl-5-nitro-benzoic, acid is used as the starting material, the condensation to the anthraquinone is referred to in the specification and claims as being effected by the removal of one mole of water, even though actually it may be NaOH that is eliminated.

We are aware that numerous details of the process may be varied through a wide range without departing from the principles of this invention, and we therefore, do not pur pose limiting the patent granted hereon,

otherwise than necessitated by the prior art.

We claim as our invention:

1. The process of preparing Q-nitro-anthraquinone-7-sulpho-acid which comprises treatmg 4-sulpho-2-benzoyl-5-nitro-benzoic acid with 25% oleum as dehydrating agent at an elevated temperature, diluting up the ring-closing mass With Water and filtering ofl the product.

2. As a new article of manufacture, a 2 nitro-anthraquinone-7-sulpho acid compound having in the form of its free acid most probably the following chemical constitution:

3. A process of preparing Q-nitro-T-sulpho anthraquinone, comprising dissolving, as starting material, isulpho-2 benzoyl5-n1- tro-benzoic acid in 25% oleum, and heating the solution to to (1., to remove a mole of water from the starting material.

4. A process of preparing 2-nitro-7-sulpho anthraquinone, comprising dissolving, 4' sulpho-Q-benzoyl-5-nitro-benzoic acid in concentrated sulphuric acid, heating the solution to 145 to 150 C., and diluting and cooling the solution to precipitate out Q-nitro- 7-sulpho-anthraquinone.

In testimony whereof We have hereunto subscribed our names at Carrollville, Milwaukee County, Wisconsin.

IVAN GUBELMANN. HENRY J. WEILAND. ()TTO STALLMANN. 

